Delegate To Update A List Box?
Mar 27, 2012
I've been fooling around with this for two hours and getting nowhere. I want to update a list box on a form with some text. Unfortunately the event that calls for the update is a timer which gives me a cross thread error.The listbox relies on a combo box which tells it the number of items to display. Here's my sub that performs the update.
Public Sub EventUpdate(ByVal EventMsg As String)
Dim DateTimeStamp As String = Format(DateAndTime.Now, "MM/dd hh:mm:ss")
With lbxEvents
[code].....
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Jan 30, 2010
from the documentation we have this: Multicast Delegate: Represents a multicast delegate; that is, a delegate that can have more than one element in its invocation list.
so am i right to say that Multicast delegate is no different from a normal delegate other than the fact that it has arguments. so System.Action is a 'normal' delegate whereas System.Action(T)(Byval obj as T) is a multicast delegate?
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Sep 25, 2009
I have used delegates multiple times over the years but for some reason this very simple code isn't working:Form has one button and on textbox. Simply trying to update the textbox from another thread and although it looks fine it's not working.[code] the parameter is being passed to the DoSomething, the UpdateTextboxText is being run and gets the correct string. But the textbox itself remains blank and I'm stumped.
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Mar 26, 2010
How would you create and use a delegate to update the text of the main form from the DoWork event of a backgoundWorker?
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Feb 16, 2009
I'm trying to search a generic list of 'User' business objects which has a property called 'Username': If (From u In colUsers Select u.Username Where Username.Equals(strUsername)).Count > 0 ThenI keep getting:Delegate to an instance method cannot have null 'this'.
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Jun 29, 2011
Here's the code I have but I'm getting syntax issues:
CODE:
I'm just looking to call ReadAndPopulate method for each item in aList. I know I can do it the traditional "For each a in aList...Next" way but wanted to learn how to do it with delegates.
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Sep 6, 2011
Is it possible to pass multiple arguments to a delegate method from a list(Of T).ForEach call?So, I'd like to pass a listbox object to the delegate routine below:
Sub test()
Dim names As New List(Of String)
names.Add("Bruce")
names.Add("Alfred")
[code]....
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Feb 9, 2010
I've created a Delegate that I intend to call Async.
[Code]...
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Jun 1, 2010
Code:
Public Class SendPings
Shared Sub New()
AddHandler Post.Saved, AddressOf Post_Saved[code].....
I get a error" Method 'Private Shared Sub Ping(item As BlogEngine.Core.IPublishable, itemUrl As System.Uri)' does not have a signature compatible with delegate 'Delegate Sub WaitCallback(state As Object)'.
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Sep 21, 2010
I think (?) this is about object design, and perhaps about structural and/or creational patterns. But a bit hard to say when I only know a couple of patterns yet.[code]But... what if we INSTEAD want each Product instance only to (in some way) refer to one instance of a specific list of Components. So we wan't to save the products list to one file, and the components list to another file. Then would I build the objects the same way, or different? So let's then say we have now Class B as below. [code]
1. Will not need to update each component variable of the products list when the components list changes.
2. If the Product object shall be shown in a DataGridView, for editing properties, it seems easier to implement the selection of the component property.
Is this wrong approach? Is it suitable in some cases, and if so, when? Are there other solutions I perhaps am not aware of that would be appropriate? Is this about structural design patterns? and if so, can the alternatives above be catagorized to some pattern type? I don't really know exactly what I'm looking for.. But I think probably I'm looking to understand whether the object design will be determined by the way the objects are saved.. And if i shall save the objects by serializing to file, vs saving to a database, would I create the business objects differently?
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Mar 23, 2010
I am trying to write a VB.NET alternative to a C# anonymous function.I wish to call Threading.SynchronizationContext.Current.Send which expects a delegate of type Threading.SendOrPostCallback to be passed to it. The background is here, but because I wish to both pass in a string to MessageBox.Show and also capture the DialogResult I need to define another delegate within. I am struggling with the VB.NET syntax, both from the traditional delegate style, and lambda functions.My go at the traditional syntax is below, but I have gut feeling it should be much simpler than this:
Private Sub CollectMesssageBoxResultFromUserAsDelegate(ByVal messageToShow As String, ByRef wasCanceled As Boolean)
wasCanceled = False
[code].....
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Jan 23, 2012
i am trying to 'Update' an item in a list The idea i was try to use was going to be to remove the item then add it again. so far this is the code i have
[code]...
The problem i am having is here,Tempcarmake has a Make property which holds the car make eg Honda, Ford, VW i want to find the item in the that has the same Make as the TEMPcarmake that the user has been using
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Mar 9, 2012
I am a bit new to linq, I am only using linq for filtering the data. [code]...
Con.Numbers is a dictionary, but now I converted it into a list, hence the above code wont work with list[code]....
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Jul 6, 2010
I'm working on a project for a client (he wanted it in VB.NET so I dont have a choice) and have hit a wall. I have a Product class, and a List(Of Product) that I'm using to store products in while a new order is being built. The problem I'm running into is updating the Quantity value of a product if it's found in the list (instead of adding the product again).
[Code]...
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Mar 21, 2012
I'd like to write an app that would allow users to modify existing records in a WSS sharepoint list and/or create new records.I feel confident that its possible, but I just don't know exactly how. Sharepoint access, for me, is accessed with domain credentials, so I"d need some method for getting those from the user, in the winform, and passing those along to the WSS server.
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Jul 8, 2010
I'm working with Windows Forms - VB.NET.Here's what I have:
A ListView with checkboxes set to True
A Button (triggers the update)
A database table with similar fields as the ListView
What I want to happen:when the user clicks the Button, all items on the ListView with checkbox checked will be updated.My progress:I've already collected the ID of the checked items and stored them in an array. I'll be using this to update the database table.I don't know how to put them in the SqlCommand.Parameters Also, I don't know the update command for such scenario (where in/exist (@parameters))
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Aug 5, 2009
Not sure if I have the correct subject line. Here is my issue. I have a form with 2 GridView. One GridView has a list of all zipCodes. The users is to select a location from a dropdown list, then select the zipcodes he/she wants to be assigned to that location and then click the "Add" button. The zipcodes then appear in the second GridView. When the user clicks the "Save" button, the data is sent to the database. The is also a "Remove" to remove zipcode(s) in the second GridView.
How do I track changes only in the second GridView. There could be 1000's of zipcode in the second GridView. Do I just remove and re-insert the list for that location evertime the user click save? I was thinking of using a DataSet, add DataRows and then update, however I am not using a DataAdapter to load my dataset, so there is no way for me to use DataAdapter.Update(ds). I am using the SQLHelper.ExecuteDataset(parms)
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Mar 29, 2012
I have a textbox which will accept a user input for a email address or phone number.I want to using a new thread do a search for various results and populate a listbox.I know i need to do this in another thread so my main form will still operate but how can I do this? I've never used threads before and I know it's tricky to get the values from a textbox and also update a list box on another thread.
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Jun 8, 2011
I'm working with Windows Forms - VB.NET.
Here's what I have:
A ListView with checkboxes set to True A Button (triggers the update) A database table with similar fields as the ListView
What I want to happen:
when the user clicks the Button, all items on the ListView with checkbox checked will be updated.
My progress: I've already collected the ID of the checked items and stored them in an array. I'll be using this to update the database table.
The problem: I don't know how to put them in the SqlCommand.Parameters Also, I don't know the update command for such scenario (where in/exist (@parameters))
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Apr 2, 2011
I have a List(Of SomeObject) that I enumerate over using a For Each loop. This SomeObject contains a Property that references another Object, as such
Class SomeObject
Public Property Another As AnotherObject
Get
[Code]....
If not, what is a valid way to do it? (ordinary for loop perhaps?)
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Jan 15, 2012
i need to use the update in the main class to access the list in the footballadmin and then display each in a list box but i cant get it to work.
Imports Football
Public Class FootballAdmin
Private fTeam As List(Of FootballTeams)
[Code]......
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Jul 5, 2010
I have repeater which shows a list of users and there roles. There is also a dropdown list to chnage there role see below
<td><asp:DropDownList ID="ddlChangeType" class="controlwidth100" runat="server" AutoPostBack="true" OnSelectedIndexChanged="change" /></td>
the change event works but what I need is the ID of the row so the user can be updated.
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Sep 19, 2011
I have some MdiChildren that have their form titles updated. However, in the MdiParent, the "Windows" Menu does not update their titles when something changes until I change MdiChildren focus.
how to forcibly make the MdiChildren Menu list update?
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Nov 1, 2010
My listview clears and updates every 2seconds. Is there an easy to refresh the list information without clearing first? Like taskmanager
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Apr 20, 2009
I need to update my array when the user checks a box in a checked list box. I have been struggling with this for awhile and have it working almost perfectly. It adds items just fine, but when I try to remove them it won't do it until I check another box.I have a CheckedListBox called fields, and a ListBox called included, and an array called fieldsArry.Here is the code when the user checks a box:
Private Sub fields_ItemCheck(ByVal sender As Object, ByVal e As System.Windows.Forms.ItemCheckEventArgs) Handles fields.ItemCheck
'We do not want to call the updateFieldArray function when it is just loading up the fields
'because those will already be in our array, but we want to call it all other times.
[code]....
I know why it is only working on one and not the other - my problem is figuring out how to get it to work on both. For whatever reason (this drives me crazy sometimes) when I check a box in the CheckedListBox it runs all the code I put in there before it even checks the box. So I can't just reference that box as a checked box until after all the code in the itemCheck event is finished. I remedied this in the updateFieldArray by including the currently selected item as a included item, which means that even when they are trying to uncheck something (remove it from the array) it is selected and will be included.
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May 2, 2011
I have a List "MyList(of MyStruct)"
[vbcode]
Public Structure MyStruct
Public ID as Integer
Public Value as Integer
End Structure
[/vbcode]
At some point I need to update the Value of the member with ID=X, but I'm stuck.
Do I need to search for the index of that member using FindIndex and then set the value like MyList(index).Value=Something?
Or
Find the member itself by using Find, but how would I then set the new value?
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Apr 25, 2010
VS 2010 [RESOLVED] List(of T) update data of a specific member
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Apr 22, 2010
url...I've got a drop down inside an update panel, and I am trying to get it to allow the person using the page to add users to a list that is bound to a gridview. The list is a global variable, and on page_load I set that to the gridview's datasource and databind it. However, anytime I click the 'add a user' button, or the button to remove the user from the list. It appears like it is doing a full post back even though all these elements are inside the update Panel.[code]Now I thought the point of an update panel was to be able to update things inside of it without doing a full post_back and reloading the page. So if that's the case, why is it calling page_load everytime I click the buttons? I ran this code and debug and I see that even before any of the code associated with button press fires, page_load runs again.I tried putting the gvAssociatedUser.Datasource = associatedFaculty and the line below inside the Page.IsPostBack check, that prevented the page from working. I tried every combination of settings of the update panel for ChildrenAsTriggers and UpdateMode, and none of them worked.
I've tried won't get it to work.It wasn't causing a full postback so I was wrong as to the cause. I thought the page was doing a full post back thus resetting my associatedFaculty list global variable, but it isn't doing a full postback.The issue I am having is everytime I click btnAddUser it will add one element to the associatedFaculty list and thus bound to gvAssociatedusers. This works the first time, but the second time I click it, it overwrites the first element. So it appears like my associated Faculty list is getting reset each time I click the button?
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Jan 23, 2012
I am writing a small program to update data in a SharePoint list. Now where I cannot develop or use applications for SharePoint unless I am on a SharePoint server, I thought I would cheat the system by using Access to link to SharePoint lists, and then use Visual Basic to play with the Access tables. I need additional functionality other than what VBA can provide me, so that is why I am using the VB layer.Is it possible that this is not permitted? Whenever I try to update an item in the table, I receive the message:
"cannot update '(expression)'; field not updatable"
The word 'expression' here is not a filler I added, this is the actual error.If I try to make the edit manually in the table using Access, it works fine (I haven't tried it through Access VBA yet...).
How my code works is this:I have a Dataset added to the project which connects to the Access database. I add one of the tables to the dataset and create a Class object to reference the table adapter (essentially a Data Access Layer). I can read all of the data fine, and when a change is made in SharePoint, my application sees the updates when it refreshes. But when I try to write back to the table I get the error message above.
For
Each r As
DataRow In TableAdapter.GetData.Select("Name LIKE '*" & FileName &
"*'")
[code]....
There are other columns in the table and some of them have default null values. I only want to update these two fields, but it almost seems like this is not possible. I thought I might be somehow opening the Dataset in a Read Only mode, but I can't seem to find that option anywhere.
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Aug 8, 2011
I have the following code,
PB.ForEach(Function(x) x.Cost = GetPartCost(x.PartNumber, x.Units, x.Cost, FB))
Return PB.Sum(Function(x) (x.Cost * x.Qty))
However it always returns 0. I've checked and the GetPartCost function executes and returns a non-zero number but the list item cost properties are never updated.The property is just a simple property,
Public Property Cost() As Double
Get
Return _Cost[code]....
If I set a breakpoint in the Set of the property, it never gets hit.
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